Rajesh Kumar Prusty

CNT/polymer interface in polymeric composites and its sensitivity study at different environments

The environmental durability of polymer based composites has always been a critical concern over its short- and long-term performances. The degree of environmental degradation is supposed to have different mechanisms and kinetics at the polymer/reinforcement interfaces in comparison to the bulk polymer matrix. Differential degradation could possibly attribute a stressed state in the material, especially at the interfaces. Present review is focused on the roles of reinforcing CNT on the performance of the polymeric nanocomposites in different in-service environments (the environmental parameters include temperature, moisture, UV light, low earth orbit space environment, electromagnetic waves). It is essential to understand how the addition of CNTs in polymeric material alters the microstructure at micro- and nano-scale, and how these modifications influence the overall macroscopic behaviour, not only in its as fabricated form, but also its continuous alteration with time in the in-service environment. The technological superiority with CNT addition to polymeric materials may be advantageous, but scientific merits are here to be explored critically for a reliable and sustainable interfacial durability and structural integrity in different in-service environmental conditions.

Lifetime Prediction of Nano-Silica based Glass Fibre/Epoxy composite by Time Temperature Superposition Principle

The incorporation of nano fillers in Fibre reinforced polymer (FRP) composites has been a source of experimentation for researchers. Addition of nano fillers has been found to improve mechanical, thermal as well as electrical properties of Glass fibre reinforced polymer (GFRP) composites. The in-plane mechanical properties of GFRP composite are mainly controlled by fibers and therefore exhibit good values. However, composite exhibits poor through-thickness properties, in which the matrix and interface are the dominant factors. Therefore, it is conducive to modify the matrix through dispersion of nano fillers. Creep is defined as the plastic deformation experienced by a material for a temperature at constant stress over a prolonged period of time. Determination of Master Curve using time-temperature superposition principle is conducive for predicting the lifetime of materials involved in naval and structural applications. This is because such materials remain in service for a prolonged time period before failure which is difficult to be kept marked. However, the failure analysis can be extrapolated from its behaviour in a shorter time at an elevated temperature as is done in master creep analysis. The present research work dealt with time-temperature analysis of 0.1% SiO2-based GFRP composites fabricated through hand-layup method. Composition of 0.1% for SiO2nano fillers with respect to the weight of the fibers was observed to provide optimized flexural properties. Time and temperature dependence of flexural properties of GFRP composites with and without nano SiO2 was determined by conducting 3-point bend flexural creep tests over a range of temperature. Stepwise isothermal creep tests from room temperature (30°C) to the glass transition temperature Tg (120°C) were performed with an alternative creep/relaxation period of 1 hour at each temperature. A constant stress of 40MPa was applied during the creep tests. The time-temperature superposition principle was followed while determining the Master Curve and cumulative damage law. The purpose of a Master Curve was to determine the variation of compliance with respect to increase in time and temperature of the specimen. The shift factors at any reference temperature were determined by Arrhenius activation energy method at a far lower temperature than Tg (Glass transition temperature) and by manual shift method at a temperature near Tg (Glass transition temperature).